Method of cooling fried or sintered material

ABSTRACT

The fired or sintered material is discharged into a trough between an inclined traveling hearth and a fixed wall until the trough is substantially filled with the material. A gaseous cooling medium is conducted continuously through the fixed wall into the material in the trough, and material is carried on the traveling hearth in an upwardly inclined direction out of the trough and then horizontally away from the trough, the speed at which material is carried on the traveling hearth and the rate at which hot material is discharged into the trough being such that the depth of the horizontally traveling material on the traveling hearth is substantially less than the depth of the material in the trough.

United States Ritzman et al.

[54] METHOD OF COOLING FRIED OR SINTERED MATERIAL [72] Inventors: Horst Ritzman, Neubeckum; Otto Heinemann; WolfGoldmann, both of Ennigerloh. all of Germany [73] Assignee: Polysius A. (L, Neubeckum, Germany [22] Filed: Feb. 10, 1971 [21] Appl.No.: 114,323

Related U.S. Application Data [63] Continuation-impart of Ser. No. 846,520, July 31,

[ 51 May 30,1972

[56] References Cited UNITED STATES PATENTS 3,412,477 11/1968 Kayatz ..263/32 X FOREIGN PATENTS OR APPLICATIONS 65,672 2/1914 Austria ..1 10/40 R Primary Examiner-Frederick L. Matteson Assistant ExaminerI-Iarry B. Ramey [57] ABSTRACT The fired or sintered material is discharged into a trough between an inclined traveling hearth and a fixed wall until the trough is substantially filled with the material. A gaseous cooling medium is conducted continuously through the fixed wall into the material in the trough, and material is carried on the traveling hearth in an upwardly inclined direction out of the trough and then horizontally away from the trough, the speed at which material is carried on the traveling hearth and the rate at which hot material is discharged into the trough being such that the depth of the horizontally traveling material on the traveling hearth is substantially less than the depth of the material in the trough.

METHOD OF COOLING FRIED OR SINTERED MATERIAL CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application, 5

Ser. No. 846,520 filed July 31, 1969, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a method of cooling fired or sintered material on a traveling hearth, the upper section of which, at least in the zone where the hot material falls on the hearth, comprises a trough running transversely of the direction of movement of the hearth, the depth of the trough exceeding the normal layer thickness of the material in the hearth area.

A traveling hearth of this type has the advantage that irregularly supplied hot material can rapidly be distributed in a very short first zone of the cooler without additional aids. In the said trough there is, in fact, formed a type of conical pile, with material being continuously removed from the lower part of the traveling hearth. The considerable consequent reduction of internal friction in the loose cone leads to rapid disintegration of the cone and hence to rapid uniform distribution of the hot material over the entire width of the hearth.

Thus even if the hot material is dropped very one-sidedly into the trough formed by the traveling hearth, a layer of material rises from this trough which is largely uniform over the entire hearth width, so that completely uniform distribution of the material is ensured immediately beyond this first short zone of the traveling hearth. This type of traveling hearth cooler thus provides particularly rapid and uniform cooling of the material, high temperature of the discharged air and particularly high heat recovery.

SUMMARY OF THE INVENTION The object of the invention is to provide an improved method of cooling fired or sintered material on a traveling hearth of the type described.

According to the invention this object is achieved in that the fired or sintered material is discharged into a trough between an inclined traveling hearth and a fixed wall until the trough is substantially filled with the material. A gaseous cooling medium is conducted continuously through the fixed wall into the material in the trough, and material is carried on the traveling hearth in an upwardly inclined direction out of the trough and then horizontally away from the trough, the speed at which material is carried on the traveling hearth and the rate at which hot material is discharged into the trough being such that the depth of the horizontally traveling material on the traveling hearth is substantially less than the depth of the material in the trough.

With such a method the direction of movement of the upper section of the hearth need not be changed in the area of the trough; a relatively sharp deflection of the upper section of the hearth in the trough area is thus avoided.

Since the fired or sintered material drops onto the loose cone in the trough at a very high temperature, there is a danger that this piling of material will result in caking and sticking phenomena, which can affect the desired disintegration of the cone, i.e. the uniform distribution of hot material over the entire width of the hearth. In order to avoid this danger, it therefore seems desirable to start cooling of the material dropped on to the hearth as soon as possible. On the other hand, to provide maximum possible heat recovery the cooling air should be considerably heated up before it leaves the traveling hearth cooler.

According to the invention, these two largely contradictory requirements are met by a reasonable compromise whereby a cooling medium is conducted through the fixed rear boundary wall into the material.

With such a method of introducing a cooling medium, the material, which mainly flows from the top downwards in the trough at first, is subjected to intense counter-flow cooling very soon after it is dropped on the hearth. The cooling process is therefore initiated relatively quickly, which effectively overcomes the tendency of the material to agglomerate while still in a hot condition.

Since the cooling medium from the rear boundary wall of the trough is mostly blown into the core of the cone of material in the trough, the cooling medium is highly heated in a desirable manner before it leaves the material. Excellent heat recovery and a high terminal temperature of the cooling medium are thus achieved.

Air is preferably used as the cooling medium, although it is obviously possible to add, for instance, some water to the air to increase the cooling effect. The flow rate of the cooling medium in the vicinity of the wall apertures is preferably between 20 and meters/second.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic longitudinal section of a traveling hearth cooler for carrying out a method in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The upper section of the traveling hearth 1 comprises an obliquely rising section 2, and an adjacent hearth section 3 running substantially horizontally. Together with the fixed wall 4, the rising hearth section 2 forms a trough wherein the hot material 5 dropped from a furnace forms a conical pile 6. The hearth traveling in the direction of arrow 7 continuously removes material from the base of this conical pile 6, and in the area of the horizontally moving hearth section 3 this material forms a layer approximately uniform in thickness and much less than the height of the material in the said trough.

According to the invention, the rear boundary wall 4 of the trough containing the conical pile 6 has a number of apertures 8, through which a cooling medium, preferably air, is blown at a relatively high flow rate into the hot material in the trough (arrow 9). Wall 4 preferably has a plurality of such apertures 8, which can be individually opened and closed, so that the amount of cooling air and its entry points can be optimally adapted to the prevailing conditions.

The cooling air introduced through the apertures 8 causes intensive cooling of the hot material dropped onto the traveling hearth, mainly in the form of counter-flow cooling, since the larger proportion of the material dropped onto the cooler first travels mainly downward inside the cone in the general direction of arrow 10, only being reversed in the lower part of the trough by the rising hearth section and carried upward again (arrow 11). Since the cooling air blown in through apertures 8 must pass through practically the entire quantity of material present in the trough, the air is considerably heated before it emerges from the material in the direction of the arrows 12.

The hearth section 3 traveling substantially horizontally adjacent the rising hearth section 2 is cooled from below by a further stream of cooling air (arrows 13) passing through the pervious hearth. The hot portion of the cooling air flows out in the direction of arrow 14 and is used, for instance, as highly heated secondary air for a preceding fumace, while the cooling air from hearth section 3 is extracted as waste air (arrow 16). The cooled material is dropped from the end of the traveling hearth l (arrow 15).

Apart from the above-named advantages, feeding cooling air through the apertures 8 in the fixed wall 4 has further benefits. These apertures are readily accessible from outside so that installation and maintenance work involves no difficulty. Since also there are no movable components at this position, there are no sealing problems such as arise in blowing air through the hearth from below. Finally, the introduction of cooling air in the vicinity of the fixed wall also serves to cool this wall in desirable manner and thus prevent caking thereon.

We claim:

l. A method of cooling fired or sintered material comprising the steps of discharging the hot material into a trough between an inclined traveling hearth and a fixed wall until the trough is substantially filled with the material, conducting a gaseous cooling medium continuously through the fixed wall into the material in the trough, and carrying material on the traveling hearth in an upwardly inclined direction out of the trough and then horizontally away from the trough, the speed at which material is carried on the traveling hearth and the rate at which hot material is discharged into the trough being such that the depth of the horizontally traveling material on the traveling hearth is substantially less than the depth of the 

1. A method of cooling fired or sintered material comprising the steps of discharging the hot material into a trough between an inclined traveling hearth and a fixed wall until the trough is substantially filled with the material, conducting a gaseous cooling medium continuously through the fixed wall into the material in the trough, and carrying material on the traveling hearth in an upwardly inclined direction out of the trough and then horizontally away from the trough, the speed at which material is carried on the traveling hearth and the rate at which hot material is discharged into the trough being such that the depth of the horizontally traveling material on the traveling hearth is substantially less than the depth of the material in the trough.
 2. A method according to claim 1 wherein the velocity of the cooling medium entering the material through the fixed wall is between 20 and 100 meters per second.
 3. A method according to claim 1 wherein the cooling medium is conducted into the material through the fixed wall at a plurality of separate points.
 4. A method according to claim 1 wherein a gaseous cooling medium is also continuously conducted through the traveling hearth into the horizontally traveling material. 